Whether for or against fluoridation, this study is meaningless. It simply matched kids to water supply that served their residence.  Many don't drink the water.  Also a better determinant is total fluoride intake - either from a typical market basket analysis - or to obtain blood, urine, nail and other samples to find out just how much fluoride these kids ingested.  Fluoride is in virtually all foods and beverages, especially high in tea, ocean fish and grape juice. It's absorbed from dental products and inhaled from air pollution.  It's in some drugs and anesthetics.  It's odd that this poorly done study is getting widely publicized when there are 76 well-done studies showing that fluoride lowers IQ - even at levels commonly consumed (and not all from China).  Fluoride isn't a nutrient or essential for healthy teeth.  So there's no scientifically valid reason to be adding it to drinking water in the first place. Consuming a fluoride-free diet doesn't cause cavities.